Can you give me as many 100 yen coins as you can with my change? I really need some.
I could really use some 100 yen coins. Can you give me as many as possible with my change?
この場合、次のような言い方ができますよ。
ーCan you give me as many 100 yen coins as you can with my change? I really need some.
「おつりにできるだけたくさん百円をくれませんか。すごく必要なんです」
ーI could really use some 100 yen coins. Can you give me as many as possible with my change?
「100円玉がすごく必要なんですが、おつりにできるだけたくさんくれませんか?」
ご参考まで!